1. Field
This disclosure relates to a surface acoustic wave device and a surface acoustic wave biosensor.
2. Description of the Related Art
A surface acoustic wave (“SAW”) is not an electromagnetic wave but a mechanical wave that is generated from the movement of particles by external factors, such as thermal, mechanical, and electrical forces, and is propagated by vibrational energy, most of which is concentrated on the surface of a medium. A SAW sensor is a device that senses, e.g., detects, a target material, such as an analyte, using a surface acoustic wave.
Generally, the SAW sensor is disposed on a substrate that includes a piezoelectric material, and the SAW sensor includes a receptor, that binds to a specific target material. Thus, when a solution containing the target material flows across the SAW sensor, its characteristic wavelength is changed by physical, chemical, and/or electrical interactions between the target material and the receptor. The resulting change in a signal (e.g., the characteristic wavelength) can be used to diagnose and monitor the content of the target material.
The SAW sensor is particularly sensitive to the pressure of a liquid, as well as to the viscosity or density of a medium, and corresponding mass changes on the surface of the SAW sensor. Accordingly, precise control of the liquid is desired to minimize noise, which is a signal change due to factors other than the desirably detected mass changes, for example.